ALBANY -- Gov. Andrew Cuomo signed a package of tougher gun measures into law Tuesday evening, immediately bolstering New York's ban on assault weapons and high-capacity magazines while giving the state more power to confiscate weapons from the mentally ill.

The new law made New York the first state to enact tighter restrictions on guns after the Dec. 14 massacre at Sandy Hook Elementary School in Newtown, Conn. It came after a month of negotiations in which Cuomo applied increasing pressure -- both publicly and privately -- on legislative leaders to reach an agreement.

"I am proud to be a New Yorker today. I am proud to be part of this government," Cuomo said shortly before signing the bill around 5 p.m. "Not just because New York has the first bill, but because New York has the best bill."

The Democratic-led Assembly passed the bill Tuesday afternoon by a 104-43 vote. The state Senate, controlled by a coalition of Republicans and breakaway Democrats, approved the bill at about 11 p.m. Monday, less than three hours after Cuomo formally proposed it.

"We proceeded, one month after the tragedy of Sandy Hook, to say to the nation: It's not acceptable to ignore the common sense things governments can do to stem gun violence," said Senate Democratic Leader Andrea Stewart-Cousins, D-Yonkers.

The gun-control package makes changes and additions to a broad swath of state law, ranging from expanding background check laws to include private sales of guns and all ammunition purchases, boosting the state's power to take firearms from the mentally ill and increasing penalties for gun-related crime.

The bill includes an immediate ban on semi-automatic rifles, shotguns and pistols with a "military-style feature," such as a flash suppressor or a bayonet mount. Guns that fall into that category but were purchased before Tuesday were grandfathered in, though their owners must register their firearms with the state or sell them out of state within one year.

Magazines would be limited to a maximum capacity of seven bullets, down from the current 10. Ten-capacity magazines purchased before Tuesday will remain legal, but would become illegal if more than seven bullets are loaded into it.

The legislation would also include the "Webster provision," a mandatory life-without-parole sentence for anyone found to have killed a first responder. The provision is a reference to the Christmas Eve shooting in the Monroe County town, where two firefighters were shot and killed.

Criticism from gun-rights advocates and a number of Republicans in the state Legislature was swift.

The National Rifle Association, which had previously labeled Cuomo as "America's most-anti-gun governor," expressed "outrage" at the "draconian gun control bill that was rushed through the process."

"Governor Andrew Cuomo and the New York State Legislature orchestrated a secretive end-run around the legislative and democratic process and passed sweeping anti-gun measures with no committee hearings and no public input," the lobbying group wrote in a statement.

The Assembly's debate stretched for more than 4 1/2 hours, with various Republicans expressing dissatisfaction with the bill and with Cuomo's decision to allow a vote without the mandatory three-day aging period. Cuomo issued a "message of necessity," which allows lawmakers to vote on a bill immediately after it is introduced.

Assemblyman Steve Katz, R-Yorktown, Westchester County, said the bill -- known as the New York Secure Ammunition and Firearms Enforcement Act, or NY SAFE -- is based on Cuomo's "misguided, egotistic notion that this will advance his presidential aspirations."

Cuomo is often mentioned as a potential Democratic presidential hopeful in 2016.

"We haven't saved any lives tonight except for one -- the political life of a governor who wants to be president," Sen. Greg Ball, R-Patterson, Putnam County, said during the Senate vote Monday.

Cuomo defended his decision to rush the legislation to a vote, which he said was in part to prevent a run on sales of soon-to-be-banned assault weapons.

"As soon as people found out that I was proposing a specific law that was going to ban the sale of assault weapons, we were afraid it would actually cause a rush on the market on people who wanted to buy assault weapons," Cuomo told reporters.

The new gun laws received praise from New York City Michael Bloomberg, a staunch gun-control advocate whose Mayors Against Illegal Guns initiative has aired television advertisements pushing for tougher laws.

"The responsible and comprehensive gun reform bills the governor signed into law today will help keep guns away from criminals and others who are already prohibited from purchasing them," Bloomberg said in a statement.